Increasingly stringent environmental regulations will require significant reductions in the sulfur content of transportation fuels. For example, by the end of this decade, maximum sulfur levels for distillate fuel will be limited to 10 wppm in Europe and Japan and 15 wppm in North America. To meet these ultra-low sulfur requirements without expensive modifications to existing refineries, it will be necessary to design a new generation of catalyst that has very high activity for desulfurization, particularly for distillate fuels at low to medium pressure.
US Published Patent Application 2008/0132407 describes recently developed catalysts in an attempt to meet the increased activity needs for ultra-low sulfur processing. The catalysts described in US 2008/0132407 provide an activity benefit over conventional catalysts. However, the long term stability of the catalysts is not proven.
What is needed is a bulk catalyst with improved stability and/or integrity for long term operation at high activity.